In the refining of crude vegetable oils, it is conventional to remove phosphatides (frequently referred to as lecithin) from the oil. This process is commonly referred to as "degumming". Degumming is typically achieved by hydrating the lecithin-containing crude oil and recovering the insoluble hydrated lecithin (frequently referred to as wet gum) from the oil. A commercial lecithin product is then obtained by drying the wet gum. Such commercial lecithin products generally have an acetone insoluble (A.I) of at least 50 and are most typically within about the 60 to about 65 A.I. range.
Certain chemical reagents such as acid anhydrides may be added, in small amounts, to crude vegetable oil to facilitate the wet gum separation and to improve upon the purity and quality of the degummed oil. The degree of ethylenic unsaturation, as reflected by its iodine value (I.V.), is not appreciably altered by the addition of a small amount of acid anhydride.
Commercial lecithins characteristically possess relatively poor hydrophilic properties. The lecithin products wet poorly and non-uniformly when dispersed into water. The unmodified lecithin products generally require a high shear and elevated temperatures (e.g., 120.degree. F.) to uniformly disperse into water and form stable emulsions. These undesirable attributes severely limit their utility for oil-in-water type applications.
The art has sought to overcome these hydrophilic shortcomings by numerous different approaches. One approach has been to chemically or enzymatically modify ordinary lecithin to improve upon its hydrophilicity. Another approach has been to remove the antagonistic components thereof. A still further approach has been to incorporate or use other compensatory additives to improve upon its water-dispersibility.
Most chemical derivitization processes, which reportedly improve upon the water-dispersibility properties of ordinary lecithin, result in a significantly lower iodine value due to derivitization of ethylenic unsaturated groups with the reactants, alteration of the acid value of this phosphatide mixture, or partial hydrolysis of the long chain fatty acid esters. The chemical modification generally introduces hydrophilic substituents into the fatty acid ester group which in turn renders the lecithin more hydrophilic. Such chemically modified lecithin products typically have an I.V. of less than 50. Illustrative thereof is U.S. Pat. No. 2,629,662 by Julian et al. which discloses peroxide and acid treatment of a 100 I.V. crude soybean lecithin phosphatide to provide a hydrolyzed lecithin having a 35 I.V. In U.S. Pat. No. 3,823,170 by Seaberg and Hayes, the emulsification properties of lecithin are significantly improved by treating an organic acid anhydride treated wet-gum with a base under conditions sufficient to provide a dry phosphatide product of an acid value between about 10 to about 25. Acid and base hydrolysis of crude lecithin reportedly improves its wetting properties. Partial hydrolysis of crude lecithin emulsions with lipase has also been indicated in Danish Pat. No. 101,649 as improving the lecithin emulsification properties.
The extraction of certain antagonistic components from crude lecithin has also been reported as a means to improve upon the emulsification properties of lecithin. Glyceride extraction coupled with choline and cephalin enrichment reportedly improves the water-in-oil emulsifying properties of lecithin. U.S. Pat. No. 3,661,946 by Pardun discloses alcohol extraction provides an enriched choline extract. Similarly, enriched choline lecithins for oil-in-water applications have been reported in U.S. Pat. Nos. 2,849,318 and 2,724,649.
A host of chemical surface active agents are commonly available for enumerable industrial, pharmaceutical, cosmetic, animal feed, food, chemical, etc. applications, including a wide variety of hydrophobic and hydrophilic systems. The chemical composition, the functional properties, emulsifier type (amphoteric, cationic, nonionic, anionic), the HLB, compatibility with various ingredients and combinations, etc. of such surface active agents differ significantly even within the closely related surface active agent classes. Emulsifier combinations (sometimes 3 or more different emulsifiers) are frequently used to achieve the desired emulsification result in many product applications.
Vegetable phosphatide mixtures, especially soy lecithins, are used individually or emulsified in the preparation of fat-containing fodders and foods. They are most effective in the stabilization of water/oil emulsions and less effective in oil/water systems. U.S. Pat. No. 3,208,857 by Howard et al. discloses fluid shortening stabilized with a low-iodine value (e.g., less than 15), hydrogenated vegetable phosphatides and edible high molecular weight surface active adjuncts. Howard et al. mentions a host of potential surface active agents. Oils emulsified in water by a hydrogenated lecithin supplemented with other food grade emulsifiers for use in an aerosol spray release product are reported in U.S. Pat. No. 3,661,605 by Rubin et al. An emulsifier combination of edible phospholipids consisting essentially of phospholipids and mono- and diester mixtures of sorbitol are reported in U.S. Pat. No. 3,560,225 by Wonsiewicz while U.S. Pat. No. 3,360,378 discloses a margarine substitute containing margarine oil and hydrolyzed lecithin in combination with other surface active agents. Similarly Swicklik in U.S. Pat. No. 3,493,387 indicates the inferior cold whipping activity may be improved by an emulsifier system comprised of hydroxylated lecithin, fatty acid monoesters of glycerol and fatty acid esters of 1,2propanediol. A water-dispersible lecithin is reportedly prepared under U.S. Pat. No. 2,193,873 by dissolving the lecithin in ethyl lactate. Industrial Oil and Fat Products (1951) by Alton E. Bailey on pages 283-284 reports the tendency towards the use of lecithin in combination with synthetic agents prepared from a glyceride or fatty acid base. Kirk-Othmer Encyclopedia of Chemical Technology (1967), Vol. 12, reports that commercial types of lecithin may be made by mixing ordinary lecithin with nonionic and anionic surfactants. U.S. Pat. No. 2,499,017 states it is common practice to mix lecithin with polyoxylene derivatives of fatty acids or sorbitan fatty acid esters to provide a composition having acceptable wetting properties when dispersed on powdered materials.
Notwithstanding numerous attempts to correct the oil-in-water emulsification properties of ordinary and high I.V. lecithins by the addition of supplemental surface active agents, the art has been unable to discover an emulsifier system which would readily wet and disperse into cold-water systems with manual mixing to form a homogeneous, stable emulsion thereof. As a result, chemical modification of the lecithin and concomitant reduction of the iodine value thereof has afforded the most effective means of overcoming these prior art difficulties. The inventor wished to achieve a cold-water-dispersible lecithin concentrate containing less than 15% by weight edible surface active agent and an ordinary high-I.V. lecithin which could be manually dispersed into coldwater to form a stable oil-in-water emulsion.